High activity vanadium-based catalyst

ABSTRACT

A vanadium-based catalyst system is treated with an ether as a means of enhancing catalyst activity and polymer productivity.

FIELD OF THE INVENTION

This invention relates to a vanadium-based catalyst suitable forproducing ethylene polymers at enhanced levels of catalyst activity andpolymer productivity.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,508,842 discloses a highly active vanadium-containingcatalyst suitable for producing ethylene polymers comprising:

(A) a solid catalyst component consisting essentially of

(1) an inorganic carrier, as support for

(2) the reaction product of (a) a vanadium trihalide and (b) an electrondonor, and

(3) a boron halide or alkylaluminum modifier,

(B) an alkylaluminum cocatalyst, and

(C) a halohydrocarbon polymerization promoter.

U.K. patent 1,015,054 likewise discloses vanadium-containing catalystcompositions useful in polymerizing unsaturated aliphatic compounds.Such compositions are obtained by mixing together a vanadium compoundand an addition compound of an aluminum alkyl with diisopropyl ether.

According to this reference, the addition compound can be formed fromequimolar amounts of the aluminum alkyl and the diisopropyl ether, butan excess of the ether is preferred as the rate of polymerizationincreases with the concentration of ether.

Japanese patent publication 61-126111 (Japanese patent application Ser.No. 84/248159) is yet another reference which disclosesvanadium-containing catalyst compositions useful in polymerizingolefins. The catalyst compositions of this reference are prepared bycombining (a) the reaction product of vanadium tetrachloride with anether or ester with (b) an organoaluminum compound which has beenmodified with an ether, ester or ketone.

According to this reference, polymerization activity is enhanced by theuse of such catalyst. However, this activity enhancement appears to bepeculiar to vanadium tetrachloride based catalysts.

SUMMARY OF THE INVENTION

In accordance with the present invention, it has now been discoveredthat ethylene polymers can be produced at enhanced levels of catalystactivity and polymer productivity employing a vanadium-based catalystsystem comprising:

(A) a solid catalyst component consisting essentially of

(1) a solid, particulate, porous inorganic carrier, as support for

(2) the reaction product of (a) a vanadium trihalide and (b) an electrondonor, and

(3) a boron halide or aluminum modifier,

(B) a triethylaluminum cocatalyst,

(C) a halohydrocarbon polymerization promoter, and

(D) an ether activity enhancer having the formula:

    R.sup.1 --O--R.sup.2

wherein:

R¹ and R² are independently monovalent hydrocarbon radicals free ofaliphatic unsaturation containing from 1 to 20 carbon atoms, or togethermake up an aliphatic ring containing from 2 to 20 carbon atoms.

DETAILED DESCRIPTION OF THE INVENTION

The vanadium-containing catalyst systems containing an ether activityenhancer in accordance with the present invention have been found to besignificantly more active than like catalyst systems which do notcontain such ether. As a result, it is possible to produce ethylenepolymers at enhanced levels of catalyst activity and polymerproductivity by the use of such catalyst systems. Surprisingly, however,this activity enhancement has been found to be peculiar to catalystsystems employing triethylaluminum as cocatalyst, and such activityenhancement is not obtained when other alkylaluminum compounds areemployed as cocatalyst.

Catalyst component (A) consists essentially of:

(1) a solid, particulate, porous inorganic carrier, as support for

(2) the reaction product of (a) a vanadium trihalide and (b) an electrondonor, and

(3) a boron halide or alkylaluminum modifier.

The vanadium trihalide which is reacted with the electron donor in thepreparation of catalyst component (A) is Preferable vanadiumtrichloride, although the halogen present in said vanadium trihalide maybe chlorine, bromine or iodine, or any mixture thereof.

The electron donor employed is a liquid, organic Lewis base in which thevanadium trihalide is soluble.

Suitable electron donors include alkyl esters of aliphatic and aromaticcarboxylic acids, aliphatic ketones, aliphatic amines, aliphaticalcohols, aliphatic ethers and cycloaliphatic ethers. Particularlyuseful are alkyl esters of saturated aliphatic carboxylic acidscontaining from 1 to 4 carbon atoms; alkyl esters of aromatic carboxylicacids containing from 7 to 8 carbon atoms; aliphatic ketones containingfrom 3 to 6 carbon atoms, preferably from 3 to 4 carbon atoms; aliphaticamines containing from 1 to 14 carbon atoms, preferably from 2 to 8carbon atoms; aliphatic alcohols containing from 1 to 8 carbon atoms,preferably from 2 to 8 carbon atoms; aliphatic ethers containing from 2to 8 carbon atoms, preferably from 4 to 5 carbon atoms; andcycloaliphatic ethers containing from 4 to 5 carbon atoms, preferablymono- or di- ethers containing 4 carbon atoms. The aliphatic andcycloaliphatic ethers are most preferred, particularly tetrahydrofuran.If desired, these electron donors may be substituted with one or moresubstituents which are inert under the reaction conditions employedduring reaction with the vanadium trihalide, as well as duringpreparation of and polymerization with catalyst component (A).

The modifier employed in the preparation of catalyst component (A) is aboron halide or alkylaluminum compound having the formula:

    MX.sub.a

wherein:

M is boron or AlR³ .sub.(3-a) wherein each R³ is an alkyl radicalcontaining from 1 to 14 carbon atoms, which radicals may be the same ordifferent,

X is selected from the group consisting of fluorine, chlorine, bromineand iodine, and mixtures thereof, and

a is an integer having a value of 0, 1 or 2, provided that a is 3 when Mis boron.

Preferably any halide present in the modifier is chlorine, and any alkylradicals present contain from 1 to 6 carbon atoms. Such alkyl radicalsmay be cyclic, branched or straight chain, and may be substituted withone or more substituents which are inert under the reaction conditionsemployed during preparation of and polymerization with catalystcomponent (A). Diethylaluminum chloride is preferred.

A solid, particulate, porous inorganic material is employed as carrierin the preparation of catalyst component (A). The carrier serves assupport for the vanadium trihalide/electron donor reaction product, andthe boron halide or alkylaluminum modifier. Suitable carriers includesuch materials as oxides of silicon, aluminum and zirconium, as well asphosphates of aluminum. Usually these materials have an average particlesize of from about 10 microns to about 250 microns, preferably fromabout 20 microns to about 150 microns, and a surface area of at least 3square meters per gram, preferably at least 50 square meters per gram.Polymerization activity of the catalyst can be improved by employing asilica support having an average pore size of at least 80 Angstromunits, preferably at least 100 Angstrom units. The carrier materialshould be dry, that is, free of absorbed water. Drying of the carriermaterial can be effected by heating, e.g., at a temperature of at least600° C. when silica is employed as the support.

Catalyst component (A) is prepared by treating a solid, particulate,porous inorganic carrier with:

(1) the reaction product of (a) a vanadium trihalide and (b) an electrondonor, and

(2) a boron halide or alkylaluminum modifier.

The vanadium trihalide/electron donor reaction product is prepared bydissolving at least one vanadium trihalide in at least one electrondonor at a temperature of from about 20° C. up to the boiling point ofthe electron donor. Dissolution of the vanadium trihalide in theelectron donor can be facilitated by stirring, and in some instances byrefluxing, the vanadium trihalide in the electron donor. Up to severalhours of heating may be required to complete dissolution.

After the vanadium trihalide has been dissolved in the electron donor,the reaction product is impregnated into the carrier. Impregnation maybe effected by adding the carrier to the solution of the vanadiumtrihalide in the electron donor, and then drying the mixture to removeexcess electron donor. The carrier may be added alone as a dry powderor, if desired, as a slurry in additional electron donor. Alternatively,the solution of the vanadium trihalide in the electron donor may beadded to the carrier. Ordinarily the carrier and the solution of thevanadium trihalide in the electron donor are mixed together in suchamounts that, after drying, the impregnated carrier contains from about0.05 mmoles to about 1.0 mmoles of vanadium per gram, preferably fromabout 0.3 mmoles to about 0.8 mmoles of vanadium per gram, and mostpreferably from about 0.3 mmoles to about 0.6 mmoles of vanadium pergram. The impregnated vanadium trihalide/electron donor reaction productprepared in this manner contains from about 1 mole to about 5 moles,preferably from about 2 moles to about 4 moles, and most preferablyabout 3 moles of electron donor per mole of vanadium trihalide. Excesselectron donor not actually complexed with the vanadium trihalide mayremain adsorbed on the carrier without ill effects.

The boron halide or alkylaluminum modifier is usually added to thecarrier after it has been impregnated with the vanadiumtrihalide/electron donor reaction product. However, if desired, theboron halide or alkylaluminum modifier may be added to the carrierbefore it is impregnated with the vanadium trihalide/electron donorreaction product. Addition of the modifier to the carrier may beeffected by dissolving one or more modifiers in one or more inert liquidsolvents capable of dissolving the modifier, immersing the carrier inthe solution, and then drying the mixture to remove the solvent. If themodifier is applied subsequent to the vanadium trihalide/electron donorreaction product, the solvent must be one which does not dissolve thevanadium trihalide/electron donor reaction product. The carrier may beadded to the solution of the modifier alone as a dry powder or, ifdesired, as a slurry in additional inert liquid solvent. Alternatively,the solution of the modifier may be added to the carrier. Ordinarily thecarrier and the solution of the modifier in the inert liquid solvent aremixed together in such amounts that, after drying, the carrier containsfrom about 0.1 mole to about 10 moles, preferably from about 1 mole toabout 5 moles, of modifier per mole of vanadium trihalide/electron donorreaction product present in the carrier (or to be added to the carrierif it is applied subsequent to the modifier).

Among the solvents which can be employed to dissolve the boron halide oralkylaluminum modifier are hydrocarbon solvents such as isopentane,hexane, heptane, toluene, xylene and naphtha.

Component (B) of the catalyst system of the present invention istriethylaluminum. As previously noted, the activity enhancement of thecatalyst system of the Present invention is peculiar to the use oftriethylaluminum as cocatalyst, and no significant activity enhancementis obtained when cocatalysts other than triethylaluminum are employed.

Component (C) of the catalyst system of the present invention is ahalohydrocarbon polymerization promoter having the formula

    R.sup.4 .sub.b CX'.sub.(4-b)

wherein:

R⁴ is hydrogen or an unsubstituted or halosubstituted alkyl radicalcontaining from 1 to 6 carbon atoms, which radicals may be the same ordifferent,

X' is halogen, and

b is 0, 1 or 2.

Preferred promoters include flouro-, chloro- or bromo- substitutedethane or methane such as CCl₄, CHCl₃, CH₂ Cl₂, CBr₄, CFCl₃, CH₃ CCl₃,and CF₂ ClCCl₃. Particularly preferred promoters are CH₃ CCl₃, CFCl₃,and CHCl₃.

Component (D) of the catalyst system of the present invention is anether having the formula:

    R.sup.1 --O--R.sup.2

wherein

R¹ and R² are independently monovalent hydrocarbon radicals free ofaliphatic unsaturation containing from 1 to 20 carbon atoms, or togethermake up a cycloaliphatic ring containing from 2 to 20 carbon atoms.

When R¹ and R² are independent radicals, such radicals are usuallyalkyl, cycloalkyl, or aryl radicals containing from 1 to 6 carbon atoms.When R¹ and R² together make up a cycloaliphatic ring, such ring usuallycontains from 2 to 6 carbon atoms. These radicals may also contain oneor more additional oxygen atoms, and may be substituted with one or moresubstituents which are inert under the reaction conditions employedduring polymerization with the catalyst system of the present invention.

The ethers employed as activity enhancers in the catalyst system of thepresent invention may be the same or different from the ethers employedas electron donors in catalyst compound (A). Such ethers include linearand cyclic aliphatic ethers such as methyl t-butyl ether, diethyl ether,diisopropyl ether, di-n-propyl ether, isopropylethyl ether, di-n-butylether, di-n-octyl ether, di-n-decyl ether, di-n-dodecyl ether, anddicyclohexyl ether; cycloaliphatic ethers such as tetrahydrofuran,tetrahydropyran, trimethylene oxide, dioxan and trioxan; and aromaticethers such as diphenyl ether and anisole.

Polymerization is effected with the catalyst system of the presentinvention by contacting ethylene, or a mixture of ethylene and at leastone alpha-olefin having 3 to 8 carbon atoms, with the four components ofthe catalyst system, i.e., the solid catalyst component, thetriethylaluminum cocatalyst, the halohydrocarbon polymerizationpromoter, and the ether activity enhancer. Polymerization can beeffected employing either solution, slurry or gas phase techniques.Suitable fluid bed reaction systems are described, e.g., in U.S. Pat.Nos. 4,302,565, 4,302,566 and 4,303,771, the disclosures of which areincorporated herein by reference.

The solid catalyst component, triethylaluminum cocatalyst,polymerization promoter, and ether activity enhancer can be introducedinto the polymerization reactor through separate feed lines or, ifdesired, two or more of the components may be partially or completelymixed with each other before they are introduced into the reactor. Inany event, the triethylaluminum cocatalyst and polymerization promoterare employed in such amounts as to provide a molar ratio of the promoterto the triethylaluminum cocatalyst of from about 0.1:1 to about 10:1,preferably from about 0.2:1 to about 2:1, and the triethylaluminumcocatalyst and the solid catalyst component are employed in such amountsas to provide an atomic ratio of aluminum in the cocatalyst to vanadiumin the solid catalyst component of from about 10:1 to about 400:1,preferably from about 15:1 to about 60:1.

The amount of ether employed in the catalyst system of the presentinvention depends upon the particular ether employed and the degree ofcatalyst activity enhancement desired. Generally, at constanttemperature, catalyst activity increases as the molar ratio of ether totriethylaluminum cocatalyst increases. However, below a ratio of about0.2:1, activity enhancement is minimal. Further, beyond a ratio of about0.8:1, enhancement of catalyst activity begins to diminish, and finallyat a ratio in excess of about 1.0:1, activity decreases to a level belowthat of like catalysts which do not contain such ether. For this reason,the ether is generally employed in amounts such as to provide a molarratio of ether to triethylaluminum cocatalyst of from about 0.2:1 toabout 1.0:1, preferably from about 0.5:1 to about 0.8:1. Ifpolymerization is conducted in gas phase, e.g., in a fluidized bed,however, it may be desirable to employ somewhat greater amounts of etherto obtain optimum results. If desired, the ether may be pre-reacted withthe triethylaluminum cocatalyst before it is introduced into the reactorto form a Lewis acid/base adduct.

The triethylaluminum cocatalyst, polymerization promoter, and etheractivity enhancer may be introduced into the reactor dissolved in aninert liquid solvent, i.e., a solvent which is nonreactive with all thecomponents of the catalyst system as well as all the components of thereaction system. Hydrocarbons such as isopentane, hexane, heptane,toluene, xylene, naphtha and mineral oil are preferred for this purpose.Generally, such solutions contain from 1 weight percent to 75 weightpercent of these materials. If desired, less concentrated or moreconcentrated solutions can be employed, or, alternatively, thetriethylaluminum cocatalyst, polymerization promoter, and ether activityenhancer can be added in the absence of solvent, or, if desired,suspended in a stream of liquified monomer. When a solvent is employedand polymerization is conducted in gas phase, the amount of solventintroduced into the reactor should be carefully controlled so as toavoid the use of excessive quantities of liquid which would interferewith such polymerization.

The solvents employed to dissolve the triethylaluminum cocatalyst,polymerization promoter, and ether activity enhancer may also beemployed to introduce the solid catalyst component into the reactor.Higher boiling solvents, such as mineral oil, are preferred for thispurpose. While the solid catalyst component may also be introduced intothe reactor in the absence of solvent or suspended in liquified monomer,such solvents may be employed to disperse the solid catalyst componentand facilitate its flow into the reactor. Such dispersions generallycontain from 1 weight percent to 75 weight percent of the solid catalystcomponent.

The alpha-olefins which may be polymerized with ethylene contain from 3to 8 carbon atoms per molecule. These alpha-olefins should not containany branching on any of their atoms closer than two carbon atoms removedfrom the double bond. Suitable alpha-olefins include propylene,butene-1, pentene-1, hexene-1, 4-methyl-pentene-1, heptene-1 andoctene-1. The preferred alpha-olefins are propylene, butene-1, hexene-1,4-methylpentene and octene-1.

The temperature employed during polymerization can vary from about 10°C. to about 115° C., preferably from about 80° C. to about 110° C., whenpolymerization is effected in gas phase or in a slurry, and from about150° C. to about 250° C. when polymerization is effected in a solution.When polymerization is conducted in gas phase, the temperature, ofcourse, must be maintained below the sintering temperature of thepolymers produced in order to prevent polymer agglomeration. On theother hand, the temperature employed during gas phase polymerizationsmust be sufficiently elevated to prevent substantial condensation of thereaction mixture to the liquid state, as such condensation will causethe polymer particles being produced to cohere to each other andlikewise aggravate the polymer agglomeration problem. This difficulty isnormally associated with the use of alpha-olefins having 5 or morecarbon atoms which have relatively high dew points. While some minorcondensation is tolerable, anything beyond this will cause reactorfouling.

The pressure employed can vary from subatmospheric to superatmospheric.Pressures of up to about 7000 kPa, preferably of from about 70 kPa toabout 3500 kPa, are suitable for gas phase, slurry and solutionpolymerizations.

If desired, polymerization may be conducted in the presence of an inertgas, i.e., a gas which is nonreactive under the conditions employedduring polymerization. The reactor should, however, be maintainedsubstantially free of undesirable catalyst poisons, such as moisture,oxygen, carbon monoxide, carbon dioxide, acetylene, and the like.

When polymerization is conducted in a fluid bed, the superficial gasvelocity of the gaseous reaction mixture through the bed must exceed theminimum flow required for fluidization in order to maintain a viablefluidized bed.

The polymers produced with the catalyst system of the present inventionhave a melt index of from greater than 0 g/10 minutes to about 500 g/10minutes, usually of from about 0.1 g/10 minutes to about 100 g/10minutes. The melt index of a polymer varies inversely with its molecularweight and is a function of the hydrogen/monomer ratio employed in thereaction system, the polymerization temperature, and the density of thepolymer. Thus, the melt index is raised by increasing thehydrogen/monomer ratio, the polymerization temperature, and/or the ratioof higher alpha olefin to ethylene employed in the reaction system.

The polymers produced with the catalyst system of the present inventionare also characterized by a density of from about 0.86 g/cm³ to about0.96 g/cm³. Such polymers generally contain at least 50 mol percent ofpolymerized ethylene and no more than 50 mol percent of polymerizedalpha olefin containing from 3 to 8 carbon atoms and, optionally,polymerized diene. When polymerized diene is present, the polymerordinarily contains from 0.01 mol percent to 10 mol percent of at leastone such diene, from 6 mol percent to 55 mol percent of at least onepolymerized alpha olefin containing from 3 to 8 carbon atoms, and from35 mol percent to 94 mol percent of polymerized ethylene.

The following Examples are designed to illustrate the process of thepresent invention and are not intended as a limitation upon the scopethereof.

The properties of the polymers produced in the Examples were determinedby the following test methods:

Melt Index (MI)

ASTM D-1238, Condition E. Measured at 190° C. and reported as grams per10 minutes.

Flow Index (FI)

ASTM D-1238, Condition F. Measured at 10 times the weight used in themelt index text above.

Melt Flow Ratio (MFR)

Ratio of Flow Index : Melt Index.

Activity

Activity values are normalized values based upon grams of polymerproduced per mmol of vanadium in the catalyst per hour per 100 psi ofethylene polymerization pressure.

EXAMPLE 1 Impregnation of Carrier with VCl₃ /THF Reaction Product

To a flask equipped with a mechanical stirrer were added 4 liters ofanhydrous tetrahydrofuran (THF), followed by 64 grams (0.406 mole) ofsolid VCl₃. The mixture was heated under nitrogen at a temperature of65° C. for 5 hours with continuous stirring in order to completelydissolve the VCl₃.

Eight hundred grams (800 g) of silica gel were dehydrated by heatingunder nitrogen at a temperature of 600° C. for 20 hours. The dehydratedgel was added to the solution prepared as above, and the mixture wasrefluxed for one hour under nitrogen. At the end of this time, themixture was heated at a temperature of 55° C. for about 6 hours under apurge of dry nitrogen to produce a dry, free-flowing powder containingabout 8 weight percent THF.

EXAMPLE 2 Treatment of Carrier with Diethylaluminum Chloride

Five hundred grams (500g) of the silica carrier impregnated with VCl₃/THF reaction product in accordance with Example 1 were slurried in 4liters of anhydrous hexane. The slurry was continuously stirred while a10 weight percent solution of diethylaluminum chloride in anhydroushexane was added over a period of 30 minutes. The impregnated carrierand the diethylaluminum chloride solution were employed in amounts thatprovided an atomic ratio of aluminum to vanadium of 2.5:1. Afteraddition of the diethylaluminum chloride solution was complete, themixture was heated at a temperature of 45° C. for about 6 hours under apurge of dry nitrogen to produce a dry, free-flowing powder.

EXAMPLES 3-25 Copolymerization of Ethylene With Hexene-1

Examples 3-25 illustrate the copolymerization of ethylene with hexene-1using the catalyst system of the present invention.

EXAMPLES 3-6

The solid catalyst component prepared as described in Example 2 wasemployed together with triethylaluminum, as cocatalyst; chloroform(CHCl₃), as polymerization promoter; and diisopropyl ether, as activityenhancer, to copolymerize ethylene and hexene-1 in a one-liter autoclavereactor.

In each polymerization, the four catalyst components were pre-mixed in a6 ounce bottle containing 100 ml of hexane before being added to thereactor. Twenty milliliters (20.0 ml) of hexene-1 were added to thepre-mixed catalyst components before the resulting mixture wastransferred to the reactor. Anhydrous conditions were maintained at alltimes.

The polymerization reactor was dried by heating at 96° C. under a streamof dry nitrogen for 20 minutes. After cooling the reactor to 50° C., 500ml of hexane were added to the reactor, and the reactor contents werestirred under a gentle flow of nitrogen. The premixed catalystcomponents were then transferred to the reactor under a stream ofnitrogen and the reactor was sealed. The temperature of the reactor wasgradually raised to 70° C. and the reactor was pressurized to a pressureof 30 kPa with hydrogen and then to 1050 kPa with ethylene. Heating wascontinued until the desired polymerization temperature of 85° C. wasattained. Polymerization was allowed to continue for 30 minutes, duringwhich time ethylene was continually added to the reactor to maintain thepressure constant. At the end of 30 minutes, the reactor was vented andopened.

Table II below sets forth the details involving the composition of thecatalysts employed in these polymerizations, as well as the reactionconditions employed during polymerization, the properties of thepolymers produced, and the productivity of each catalyst system.

Shorthand designations employed in Table II are defined as follows:

                  TABLE II                                                        ______________________________________                                        Designation     Definition                                                    ______________________________________                                        THF             Tetrahydrofuran                                               DEAC            Diethylaluminum chloride                                      TEAL            Triethylaluminum                                              TIBA            Triisobutylaluminum                                           IPE             Diisopropyl ether                                             DBE             Di- -n-butyl ether                                            MTBE            Methyl t-butyl ether                                          ______________________________________                                    

EXAMPLES 7-12

The solid catalyst component prepared as described in Example 2 wasemployed together with triethylaluminum, as cocatalyst; chloroform(CHCl₃), as polymerization promoter; and di-n-butyl ether, as activityenhancer, to copolymerize ethylene and hexene-1 in a one-liter autoclavereactor.

The procedure employed in Examples 7 and 8 was identical to that ofExamples 3-6 except that di-n-butyl ether was substituted fordiisopropyl ether.

The procedure of Example 9 was also identical except that di-n-butylether was injected into the polymerization reactor 10 minutes after thecommencement of polymerization rather than being pre-mixed with theother catalyst components.

The procedure of Examples 10-12 was also identical except that thedi-n-butyl ether was pre-mixed with the triethylaluminum cocatalystprior to being added to the other catalyst components.

The details of these polymerizations are set forth in Table II belowalong with the details of Examples 3-6.

EXAMPLES 13-19

The solid catalyst component prepared as described in Example 2 wasemployed together with triethylaluminum, as cocatalyst; chloroform(CHCl₃), as polymerization promoter; and tetrahydrofuran, as activityenhancer, to copolymerize ethylene and hexene-1 in a one-liter autoclavereactor.

The procedure employed in Examples 13-14 and 17-19 was identical to thatof Examples 3-6 except that tetrahydrofuran was substituted fordiisopropyl ether.

The procedure of Examples 15-16 was also identical except that thetetrahydrofuran was pre-mixed with the triethylaluminum cocatalyst priorto being added to the other catalyst components.

The details of these polymerizations are set forth in Table II belowalong with the details of Examples 3-12.

EXAMPLES 20-21

The solid catalyst component prepared as described in Example 2 wasemployed together with triethylaluminum, as cocatalyst; chloroform(CHCl₃), as polymerization promoter; and methyl t-butyl ether asactivity enhancer, to copolymerize ethylene and hexene-1 in a one-literautoclave reactor.

The procedure employed in Examples 20-21 was identical to that ofExamples 3-6 except that methyl t-butyl ether was substituted fordiisopropyl ether.

The details of these polymerizations are set forth in Table II belowalong with the details of Examples 3-19.

COMPARATIVE EXAMPLE A

For comparative purposes, ethylene was copolymerized with hexene-1 as inExamples 3-21 except that the use of an ether activity enhancer wasomitted. The details of this polymerization are set forth in Table IIbelow along with the details of Examples 3-21.

EXAMPLES 22-24

The solid catalyst component prepared as described in Example 2 wasemployed together with triethylaluminum, as cocatalyst;trichlorofluoromethane (CFCl₃), as polymerization promoter; andtetrahydrofuran, as activity enhancer, to copolymerize ethylene andhexene-1 in a one-liter autoclave reactor.

The procedure employed in Examples 22-24 was identical to that ofExamples 3-6 except that trichlorofluoromethane was substituted forchloroform and tetrahydrofuran was substituted for diisopropyl ether.

The details of these polymerizations are set forth in Table II belowalong with the details of Examples 3-21.

EXAMPLE 25

The solid catalyst component prepared as described in Example 2 wasemployed together with triethylaluminum, as cocatalyst;trichlorofluoromethane (CFCl₃), as polymerization promoter; anddi-n-butyl ether, as activity enhancer, to copolymerize ethylene andhexene-1 in a one-liter autoclave reactor.

The procedure employed in Example 25 was identical to that of Examples3-6 except that trichlorofluoromethane was substituted for chloroformand di-n-butyl ether was substituted for diisopropylether.

The details of this polymerization are set forth in Table II below alongwith the details of Examples 3-24.

COMPARATIVE EXAMPLE B

For comparative purposes, ethylene was copolymerized with hexene-1 as inExamples 22-25 except that the use of an ether activity enhancer wasomitted. The details of this polymerization are set forth in Table IIbelow along with the details of Examples 22-25.

COMPARATIVE EXAMPLES C-D

In Comparative Example C, ethylene was copolymerized with hexene-1 as inComparative Example A except that triisobutylaluminum was employed ascocatalyst instead of triethylaluminum.

In Comparative Example D, the procedure was repeated employingdi-n-butyl ether as an activity enhancer.

The details of these polymerizations are set forth in Table II below.

It is apparent from Comparative Examples C and D that no activity gainis obtained by the use of an ether activity enhancer whentriisobutylaluminum is employed as cocatalyst. As is apparent from thedata in Table II, however, the effect is quite different when an etheractivity enhancer is employed together with a triethylaluminumcocatalyst.

                                      TABLE II                                    __________________________________________________________________________                   Comp.                                                          EXAMPLE        Exp. A                                                                              3     4     5     6     7     8     9                    __________________________________________________________________________    Catalyst                                                                      Carrier        SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2            Precursor      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF       Modifier       DEAC  DEAC  DEAC  DEAC  DEAC  DEAC  DEAC  DEAC                 Modifier/V Ratio                                                                             2.5   2.5   2.5   2.5   2.5   2.5   2.5   2.5                  Cocatalyst     TEAL  TEAL  TEAL  TEAL  TEAL  TEAL  TEAL  TEAL                 Al/V Ratio     40    40    40    40    40    40    40    40                   Promoter       CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3           Promoter/Al Ratio                                                                            1.0   1.0   1.0   1.0   1.0   1.0   1.0   1.0                  Activity Enhancer                                                                            --    IPE   IPE   IPE   IPE   DBE   DBE   DBE.sup.1            Activity Enhancer/Al Ratio                                                                   --    0.250 0.500 0.625 0.750 0.375 0.750 0.750                Activity Enhancer/V Ratio                                                                    --    10    20    25    30    15    30    30                   Reactions Conditions                                                          Temperature, °C.                                                                      85    85    85    85    85    85    85    85                   Pressure, kPa  1050  1050  1050  1050  1050  1050  1050  1050                 Reaction time, minutes                                                                       30    30    30    30    30    30    30    30                   Polymer Properties                                                            Melt Index, g/10 min.                                                                        14    4.2   1.9   1.6   2.2   3.3   0.7   1.2                  Flow Index, g/10 min.                                                                        742   214   108   387   136   175   66.0  76.6                 Melt Flow Ratio                                                                              55    51    57    242   62    53    94    64                   Activity                                                                      g polymer/mmol 4067  3800  4902  4480  4365  4155  6372  5106                 V-Hr-100 psi C.sub.2 H.sub.4                                                  Activity Increase vs.                                                                        --    -7    21    10    7     2     57    26                   Control, %                                                                    __________________________________________________________________________    EXAMPLE        10    11    12    13    14    15    16    17                   __________________________________________________________________________    Catalyst                                                                      Carrier        SiO.sub.2                                                                           SiO.sub. 2                                                                          SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2            Precursor      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF       Modifier       DEAC  DEAC  DEAC  DEAC  DEAC  DEAC  DEAC  DEAC                 Modifier/V Ratio                                                                             2.5   2.5   2.5   2.5   2.5   2.5   2.5   2.5                  Cocatalyst     TEAL  TEAL  TEAL  TEAL  TEAL  TEAL  TEAL  TEAL                 Al/V Ratio     40    40    40    40    40    40    40    40                   Promoter       CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3           Promoter/Al Ratio                                                                            1.0   1.0   1.0   1.0   1.0   1.0   1.0   1.0                  Activity Enhancer                                                                            DBE.sup.2                                                                           DBE.sup.3                                                                           DBE.sup.4                                                                           THF   THF   THF.sup.5                                                                           THF.sup.6                                                                           THF                  Activity Enhancer/Al Ratio                                                                   0.750 0.750 0.750 0.375 0.500 0.500 0.625 0.625                Activity Enhancer/V Ratio                                                                    30    30    30    15    20    20    25    25                   Reactions Conditions                                                          Temperature, °C.                                                                      85    85    85    85    85    85    85    85                   Pressure, kPa  1050  1050  1050  1050  1050  1050  1050  1050                 Reaction time, minutes                                                                       30    30    30    30    30    30    30    30                   Polymer Properties                                                            Melt Index, g/10 min.                                                                        2.3   0.1   0.4   2.4   1.9   4.9   1.2   1.5                  Flow Index, g/10 min.                                                                        111   12    67    135   122   204   54    67                   Melt Flow Ratio                                                                              48    120   168   56    64    42    47    45                   Activity                                                                      g polymer/mmol 5938  7101  6488  4554  5874  5866  7084  5645                 V-Hr-100 psi C.sub.2 H.sub.4                                                  Activity Increase vs.                                                                        46    75    60    12    44    44    74    39                   Control, %                                                                    __________________________________________________________________________                                           Comp.                                  EXAMPLE        18    19    20    21    Exp. B                                                                              22    23    24                   __________________________________________________________________________    Catalyst                                                                      Carrier        SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2            Precursor      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF       Modifier       DEAC  DEAC  DEAC  DEAC  DEAC  DEAC  DEAC  DEAC                 Modifier/V Ratio                                                                             2.5   2.5   2.5   2.5   2.5   2.5   2.5   2.5                  Cocatalyst     TEAL  TEAL  TEAL  TEAL  TEAL  TEAL  TEAL  TEAL                 Al/V Ratio     40    40    40    40    40    40    40    40                   Promoter       CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                                                          CFCl.sub.3                                                                          CFCl.sub.3                                                                          CFCl.sub.3                                                                          CFCl.sub.3           Promoter/Al Ratio                                                                            1.0   1.0   1.0   1.0   1.0   1.0   1.0   1.0                  Activity Enhancer                                                                            THF   THF   MTBE  MTBE  --    THF   THF   THF                  Activity Enhancer/Al Ratio                                                                   0.750 1.00  0.750 1.00  --    0.450 0.625 0.750                Activity Enhancer/V Ratio                                                                    30    40    30    40    --    18    25    30                   Reactions Conditions                                                          Temperature, °C.                                                                      85    85    85    85    85    85    85    85                   Pressure, kPa  1050  1050  1050  1050  1050  1050  1050  1050                 Reaction time, minutes                                                                       30    30    30    30    30    30    30    30                   Polymer Properties                                                            Melt Index, g/10 min.                                                                        4.8   47    1.5   23    3.6   13    28    7.4                  Flow Index, g/10 min.                                                                        168   --    134   133   216   586   618   294                  Melt Flow Ratio                                                                              35    27    89    58    60    45    22    40                   Activity                                                                      g polymer/mmol 6175  2040  5945  4220  3045  4786  5250  4739                 V-Hr-100 psi C.sub.2 H.sub.4                                                  Activity Increase vs.                                                                        52    -50   46    4     --    57    72    56                   Control, %                                                                    __________________________________________________________________________                                                       Comp. Comp.                                               EXAMPLE       25    Exp.                                                                                Exp.                 __________________________________________________________________________                                                             D                                                   Catalyst                                                                      Carrier       SiO.sub.2                                                                           SiO.sub.2                                                                           SiO.sub.2                                           Precursor     VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                                                      VCl.sub.3 /THF                                      Modifier      DEAC  DEAC  DEAC                                                Modifier/V Ratio                                                                            2.5   2.5   2.5                                                 Cocatalyst    TEAL  TIBA  TIBA                                                Al/V Ratio    40    40    40                                                  Promoter      CFCl.sub.3                                                                          CHCl.sub.3                                                                          CHCl.sub.3                                          Promoter/Al Ratio                                                                           1.0   1.0   1.0                                                 Activity Enhancer                                                                           DBE   --    DBE                                                 Activity Enhancer/Al Ratio                                                                  0.750 --    0.750                                               Activity Enhancer/V Ratio                                                                   30    --    30                                                  Reactions Conditions                                                          Temperature, °C.                                                                     85    85    85                                                  Pressure, kPa 1050  1050  1050                                                Reaction time, minutes                                                                      30    30    30                                                  Polymer Properties                                                            Melt Index, g/10 min.                                                                       1.7   0.5   1.4                                                 Flow Index, g/10 min.                                                                       97    54    93                                                  Melt Flow Ratio                                                                             57    108   66                                                  Activity                                                                      g polymer/mmol                                                                              5785  6030  5936                                                V-Hr-100 psi C.sub.2 H.sub.4                                                  Activity Increase vs.                                                                       74    --    -2                                                  Control, %                                     __________________________________________________________________________     1 DBE was injected into the polymerization reactor 10 minutes after           commencement of polymerization.                                               2 DBE was premixed with TEAL cocatalyst and allowed to stand for 1 day.       3 DBE was premixed with TEAL cocatalyst and allowed to stand for 7 days.      4 DBE was premixed with TEAL cocatalyst and allowed to stand for 17 days.     5 THF was premixed with TEAL cocatalyst and allowed to stand for 1 day.       6 THF was premixed with TEAL cocatalyst and allowed to stand for 2 days. 

We claim:
 1. A catalyst system comprising:(A) a solid catalyst componentconsisting essentially of(1) a solid, particulate, porous inorganiccarrier, as support for (2) the reaction product of (a) of vanadiumtrihalide and (b) an electron donor, and (3) a boron halide oralkyl-aluminum modifier, (B) a triethylaluminum cocatalyst, (C) ahalohydrocarbon polymerization promoter, and (D) an ether activityenhancer having the formula:

    R.sup.1 --O--R.sup.2

wherein: R¹ and R² are independently monovalent hydrocarbon radicalsfree of aliphatic unsaturation containing from 1 to 20 carbon atoms, ortogether make up an aliphatic ring containing from 2 to 20 carbonatoms,said ether activity enhancer being present in an amount sufficientto provide a molar ratio of such ether to the triethylaluminumcocatalyst of from 0.2:1 to 0.8:1.
 2. A catalyst system as in claim 1wherein R¹ and R² are alkyl radicals containing from 1 to 6 carbonatoms, or together make up a cycloaliphatic ring containing from 2 to 6carbon atoms.
 3. A catalyst system as in claim 1 wherein the etheractivity enhancer is diisopropyl ether.
 4. A catalyst system as in claim1 wherein the ether activity enhancer is di-n-butyl ether.
 5. A catalystsystem as in claim 1 wherein the ether activity enhancer is methylt-butyl ether.
 6. A catalyst system as in claim 1 wherein the etheractivity enhancer is present in an amount sufficient to provide a molarratio of such ether to the triethylaluminum cocatalyst of from 0.5:1 to0.8:1.
 7. A catalyst system as in claim 6 wherein R¹ and R² are alkylradicals containing from 1 to 6 carbon atoms, or together make up acycloaliphatic ring containing from 2 to 6 carbon atoms.
 8. A catalystsystem as in claim 6 wherein the ether activity enhancer is diisopropylether.
 9. A catalyst system as in claim 6 wherein the ether activityenhancer is di-n-butyl ether.
 10. A catalyst system as in claim 6wherein the ether activity enhancer is methyl t-butyl ether.
 11. In acatalyst system comprising:(A) a solid catalyst component consistingessentially of(1) a solid, particulate, porous inorganic carrier, assupport for (2) the reaction product of (a) a vanadium trihalide and (b)an electron donor, and (3) a boron halide or alkyl-aluminum modifier,(B) a triethylaluminum cocatalyst, and (C) a halohydrocarbonpolymerization promoter,the improvement wherein an ether activityenhancer is present in the catalyst system, said ether having theformula:

    R.sup.1 --O--R.sup.2

wherein: R¹ and R² are independently monovalent hydrocarbon radicalsfree of aliphatic unsaturation containing from 1 to 20 carbon atoms, ortogether make up an aliphatic ring containing from 2 to 20 carbonatoms,said ether activity enhancer being present in an amount sufficientto provide a molar ratio of such either to the triethylaluminumcocatalyst of from 0.2:1 to 0.8:1.
 12. A catalyst system as in claim 11,wherein R¹ and R² are alkyl radicals containing from 1 to 6 carbonatoms, or together make up a cycloaliphatic ring containing from 2 to 6carbon atoms.
 13. A catalyst system as in claim 11 wherein the etheractivity enhancer is diisopropyl ether.
 14. A catalyst system as inclaim 11 wherein the ether activity enhancer is di-n-butyl ether.
 15. Acatalyst system as in claim 11 wherein the ether activity enhancer ismethyl t-butyl ether.
 16. A catalyst system as in claim 11 wherein theether activity enhancer is present in an amount sufficient to provide amolar ratio of such ether to the triethylaluminum cocatalyst of from0.5:1 to 0.8:1.
 17. A catalyst system as in claim 16 wherein R¹ and R²are alkyl radicals containing from 1 to 6 carbon atoms, or together makeup a cycloaliphatic ring containing from 2 to 6 carbon atoms.
 18. Acatalyst system as in claim 16 wherein the ether activity enhancer isdiisopropyl ether.
 19. A catalyst system as in claim 16 wherein theether activity enhancer is di-n-butyl ether.
 20. A catalyst system as inclaim 16, wherein the ether activity enhancer is methyl t-butyl ether.